/Engine/Source/Runtime/MovieScene/Public/Channels/MovieSceneChannelData.h
Find the range of keys that fall around InTime +/- InTolerance up to a maximum
void FindKeys ( [FFrameNumber](API\Runtime\Core\Misc\FFrameNumber) InTime, int32 MaxNum, int32 & OutMinIndex, int32 & OutMaxIndex, int32 InTolerance )